This invention relates to certain substituted fused heterocyclic compounds which are useful as herbicides and their agriculturally suitable compositions as well as methods for their use as general or selective preemergent or postemergent herbicides or as plant growth regulants.
New compounds effective for controlling the growth of undesired vegetation are in constant demand. In the most common situation, such compounds are sought to selectively control the growth of weeds in useful crops such as cotton, rice, corn, wheat and soybeans, to name a few. Unchecked weed growth in such crops can cause significant losses, reducing profit to the farmer and increasing costs to the consumer. In other situations, herbicides are desired which will control all plant growth. Examples of areas in which complete control of all vegetation is desired are areas around railroad tracks, storage tanks and industrial storage areas. There are many products commercially available for these purposes, but the search continues for products which are more effective, less costly and environmentally safe.
EP-A-353,902 discloses herbicidal compounds of the formula ##STR2## wherein, inter alia G and G.sup.1 are N and C; and
X, Y and Z are independently CR.sub.7 or N. PA1 Y is N or CR.sup.8 ; PA1 Z is N, CR.sup.4 or CR.sup.5 ; PA1 Q i s N, CR.sup.4 or CR.sup.5 ; PA1 R is C.sub.1 -C.sub.4 alkyl, C.sub.2 -C.sub.4 alkoxyalkyl, C.sub.2 -C.sub.4 alkenyl, C.sub.2 -C.sub.4 alkynyl, C.sub.1 -C.sub.4 alkoxy,, C.sub.1 -C.sub.4 alkylthio, C.sub.1 -C.sub.3 alkylamino or N(C.sub.1 -C.sub.3 alkyl) (C.sub.1 -C.sub.3 alkyl); PA1 R.sup.1 is H, F, Cl or CH.sub.3 ; PA1 R.sup.2 is H, halogen, C.sub.1 -C.sub.3 alkyl, C.sub.1 -C.sub.3 haloalkyl, C.sub.1 -C.sub.3 alkoxy or C.sub.1 -C.sub.3 haloalkoxy; PA1 R.sup.3 is H, halogen, C.sub.1 -C.sub.4 alkyl, C.sub.2 -C.sub.4 alkenyl, C.sub.2 -C.sub.4 alkynyl, C.sub.1 -C.sub.4 haloalkyl, C.sub.3 -C.sub.4 halocycloalkyl, C.sub.2 -C.sub.4 haloalkenyl, C.sub.2 -C.sub.4 haloalkynyl, OR.sup.6, S(O).sub.n R.sub.7 or CN; PA1 R.sup.4 is H, CN, C.sub.1 -C.sub.3 alkyl, C.sub.1 -C.sub.3 alkoxy or halogen; PA1 R.sup.5 is C.sub.1 -C.sub.4 haloalkyl, C.sub.3 -C.sub.5 halocycloalkyl, C.sub.2 -C.sub.4 haloalkenyl, C.sub.2 -C.sub.4 haloalkynyl, OR.sup.6, S(O).sub.n R.sup.7 or halogen; PA1 R.sup.6 is C.sub.1 -C.sub.4 alkyl, C.sub.3 -C.sub.4 alkenyl, C.sub.3 -C.sub.4 alkynyl, C.sub.1 -C.sub.4 haloalkyl, C.sub.2 -C.sub.4 haloalkenyl or C.sub.2 -C.sub.4 haloalkynyl; PA1 R.sup.7 is C.sub.1 -C.sub.2 alkyl or C.sub.1 -C.sub.2 haloalkyl; PA1 R.sup.8 is H, CN, C.sub.1 -C.sub.3 alkyl, C.sub.1 -C.sub.3 alkoxy or halogen; and PA1 n is 0, 1 or 2. PA1 (a) when Z is N or CR.sup.4, then Q is CR.sup.5 ; and PA1 (b) when Q is N or C R.sup.4, then Z is CR.sup.5. PA1 1. Compounds of Formula I wherein PA1 R.sup.1 is H or F; and PA1 R.sup.2 is H or F. PA1 2. Compounds of Preferred 1 wherein PA1 R.sup.3 is F, Cl, Br, C.sub.1 -C.sub.4 haloalkyl, OR.sup.6, S(O).sub.n R.sup.7 or CN; PA1 n is O; PA1 Y is N, CH or C--CN; and their mono N-oxides. PA1 3. Compounds of Preferred 2 wherein PA1 R is C.sub.1 -C.sub.3 alkyl, C.sub.2 -C.sub.3 alkoxyalkyl, C.sub.2 -C.sub.3 alkenyl, C.sub.2 -C.sub.3 alkynyl, C.sub.1 -C.sub.2 alkoxy, C.sub.1 -C.sub.2 alkylthio, C.sub.1 -C.sub.2 alkylamino and N(C.sub.1 -C.sub.2 alkyl) (C.sub.1 -C.sub.2 alkyl); PA1 R.sup.6 is C.sub.1 -C.sub.3 alkyl, allyl, propargyl, C.sub.1 -C.sub.3 haloalkyl, C.sub.2 -C.sub.3 haloalkenyl. PA1 4. Compounds of Preferred 3 wherein PA1 Z is N, CH or C--CN. PA1 2-(difluoromethoxy)-6-methyl-8-[3-(trifluoromethyl)phenyl]quinoxaline; PA1 7-methyl-3-(2,2,2-trifluoroethoxy)-5-[3-(trifluoromethyl)phenyl]-1,2,4-benz otriazine 1-oxide; PA1 7-methyl-3-(2,2,2-trifluoroethoxy)-5-[3-(trifluoromethyl)phenyl]-1,2,4-benz otriazine; and PA1 6-methyl-2-(trifluoromethyl)-8-[3-(trifluoromethyl)phenyl]quinoxaline.
Ind. J. Chem. 1980, 19B, 1011-1013 discloses without teaching herbicidal utility compounds of the formula ##STR3##